DESCRIPTION: One vital factor in prostate cancer (PCa) growth is androgen. Androgen effects are mediated through androgen-androgen receptor (A-AR) interaction that can then activate or repress its target genes. Based on this principle, androgen ablation therapy with various antiandrogens to treat PCa is still being used. However, many (if not all) PCa patients progress to an androgen-independent state leading to demise. Androgen is the only steroid hormone with two active forms (testosterone, T, vs. dihydrotestosterone, DHT) and all data thus far suggest only one AR gene exists. Further study of the mechanism of these two androgens will help determine how T or DHT can differentially regulate androgen target genes. This may allow us to develop a T- or DHT- specific antiandrogen that will help us to battle PCa with fewer side effects or prevent progression to an androgen-independent stage (because we only block one type of androgen without interfering with the action of the other type).